Molded product and method for manufacturing same

ABSTRACT

A molded product having a phase separation structure formed by photopolymerization of a photopolymerizable composition and imparting a sharp diffraction spot at a high diffraction efficiency, and a method for manufacturing same are provided. The molded product ( 1 ) comprises a matrix ( 2 ) and a multiple columnar structures ( 3 ) disposed within the matrix ( 2 ) and having an index of refraction different from the matrix ( 2 ), wherein the half width of a diffraction spot is 0.6° or less and diffraction efficiency is 10% or greater in an angular spectrum obtained by irradiation with a laser beam having an intensity distribution of standard normal distribution and a half width of the intensity distribution of 0.5°. The multiple columnar structures ( 3 ) are oriented in approximately the same direction, and are aligned in a regular lattice on a plane perpendicular to said orientation direction.

CROSS REFERENCE TO RELATED APPLICATIONS

This is continuation-in-part of U.S. application Ser. No. 12/444,960,filed Apr. 9, 2009, which is a national stage of PCT InternationalApplication No. PCT/JP2007/071234, filed Oct. 31, 2007, which claims thebenefit of Japanese Patent Application No. 2006-2966865, filed Oct. 31,2006, all of which are hereby incorporated by reference in theirentireties.

TECHNICAL FIELD

The present invention relates to a molded product such as an film usedas an optical part, with optical properties such as diffraction,polarization, or diffusion.

BACKGROUND ART

Due to their rich selection of materials and wide variety of functions,attempts to apply polymer materials for optical purposes have beengrowing in recent years. For example, polymer molded products in whichfine scale one or two-dimensional structures are formed can be used aslight control elements or light diffraction elements.

A known molded product of this type is a polymer film having a phasestructure whereby in a polymer matrix, multiple structures having anindex of refraction different from that of the matrix are oriented inthe same direction (see Documents 1 and 2). Polymer films having thistype of phase structure impart a diffraction spot when incident light isparallel to the axial direction of the structure, due to theabove-described layout of the structure. Therefore polymer films of thistype can be used as light diffraction elements for diffracting incidentlight at a specific position and a specified intensity.

A film having such a structure and a method of fabricating same is setforth in Document 1. In Document 1, the film is produced byphotopolymerizing at a fixed film thickness by irradiating with lightfrom a linear light source directed from a specified angle. Filmfabricated in this way selectively diffracts light incident at aspecific incidence angle.

Document 2 sets forth a film with a sea-island phase structure; thisfilm is formed such that a columnar island structure extends in the filmthickness direction within a sea structure.

In this method, the photo polymerizable composition is first coated ontoa substrate at a uniform thickness, then that surface is covered with amask. A large number of holes are randomly patterned into this mask.Next, ultraviolet light is shone on the surface of the photopolymerizable composition through this mask, thus forming columnarbodies which serve as the island structures. After the columnar bodiesare formed, the mask is removed and further ultraviolet radiation isshone on the film, thereby polymerizing the sea structure portions.

Document 1: JP-A-03-284702

Document 2: JP-A-11-287906

DISCLOSURE OF THE INVENTION Problems the Invention is to Solve

However, while it did function as a light control element for changinglight transmissivity depending on incidence angle, the internal phasestructure of parallel strips in the film set forth in Document 1 meantthat it had only low one dimensional regularity as a light diffractionelement, and did not diffract incident light at a high efficiency orimpart a diffraction spot exhibiting a steep angular spectrum.

The film set forth in Document 2 did not have regularity in itsarrangement of island structures, and scattered incident light,therefore it did not impart a sharp diffraction spot.

Light passing through an opening is known to spread due to diffraction.For a plane wave of wavelength λ incident on a circular aperture with aradius a, the intensity I on the image plane after diffraction is givenby the following formula for a distance L of the image plane from theaperture, and a distance r from the center of the image plane:

I=(πa ²)²[2J ₁(R)/R] ²   (1)

(R=2πar/λL)

The distance r_(min) at which the diffraction intensity in the imageplane first displays a minimum value is obtained as the first zero pointof J₁(R), i.e. R=3.83. It is known that of the entire light quantity,approximately 84% of the energy is concentrated in the circle havingradius r_(min), and r_(min) is a rough indication of the spreading ofdiffracted light from a circular aperture.

For example, if light with a wavelength of 365 nm passes through acircular aperture of a=1 μm, then r=5 μm at L=45 μm. In other words,this indicates that light passing through a circular aperture with aradius of 1 μm blurs to a circle of 5 μm radius when it advances by 45μm. It is difficult, that is, to form a 1 μm radius columnar structurewith a high aspect ratio by irradiation through a photomask only. Anexample of forming island structures using a photomask is given inDocument 2, but no consideration is given to light diffraction, and itwould consider that high aspect ratio columnar structures cannot be thusformed. That is, a film for diffracting light at a high diffractionefficiency onto a specified pattern can not be fabricated by the methodof Document 2.

As described above, it was not possible in the past to usephotopolymerization to fabricate a polymer film for imparting a sharpdiffraction spot at a high diffraction efficiency. Therefore theabove-described polymer films could not be used for optical low-passfilters and the like which required a light diffraction plate fordiffracting light in a specified pattern at a high diffractionefficiency.

The present invention was undertaken to solve this type of problem, andis a molded product having a phase structure formed byphotopolymerization of a photopolymerizable composition, with the objectof providing a molded product for imparting a sharp diffraction spot ata high diffraction efficiency, and a method for manufacturing same. Ithas the further object of providing optical low pass filters and thelike using the above-described molded product.

Means for Solving the Problems

The present invention is a molded product having a phase structurecomprising a matrix and multiple columnar structures disposed withinsaid matrix and having an index of refraction different from saidmatrix, wherein the half width of a diffraction spot is 0.6° or less,and diffraction efficiency is 10% or greater in an angular spectrumobtained by irradiation with a laser beam having an intensitydistribution of standard normal distribution and a half width of theintensity distribution of 0.5°.

In a preferred embodiment of the present invention, the multiplecolumnar structures are oriented in approximately the same direction,and are disposed in a regular lattice on a plane perpendicular to saidorientation direction.

Also, in a preferred embodiment of the present invention, the multiplecolumnar structures have approximately the same cross sectional shape inthe direction perpendicular to the orientation direction.

Also, in a preferred embodiment of the present invention, the columnarstructures have an aspect ratio of 10 or greater.

In addition, in a preferred embodiment of the present invention, thematrix and columnar structures comprise a polymerized object of anacrylic photopolymerizable composition.

The optical laminate of the present invention comprises the moldedproduct above, and an optically transparent film laminated thereto.

Also, the optical laminate of the present invention comprises theabove-described molded product and a glass substrate formed as one piecewith this molded product so as to support the molded product.

Furthermore, the optical low-pass filter of the present invention usesthe above-described optical laminate.

Furthermore, the imaging optical system of the present inventioncomprises a fixed image sensor, and the above-described low-pass filterdisposed on the photo-detection surface of the fixed image sensor via agap layer.

The present invention is a method for manufacturing a molded producthaving a phase structure, comprising a matrix formed of a photopolymerizable composition and multiple columnar structures disposedwithin said matrix, having an index of refraction different from that ofsaid matrix, said method comprising a step for injecting aphotopolymerizable composition containing a photopolymerizing monomer oroligomer and a photoinitiator into a mold; a step for disposing aphotomask having optically transmissive regions and an opticallynon-transmissive region between the mold and a light source; a firstlight irradiation step for directing parallel light from the lightsource with a wavelength half width of 100 nm or less and anapproximately uniform light intensity distribution toward thephotopolymerizable composition within the mold via a photomask andirradiating same, and for polymerizing sites irradiated with parallellight within the photopolymerizable composition into an incompletelypolymerized state; and a second light irradiation step in which thephotomask is removed and parallel light with a wavelength half width of100 nm or less and an approximately uniform light intensity distributionis further directed at and used to irradiate thephotopolymerizablephotopolymerizable composition, thereby completing thepolymerization of the photopolymerizablephotopolymerizable composition.

The present invention thus has a first irradiation step in whichparallel light is irradiated via a photomask onto a photopolymerizablecomposition filled into a mold, and a second irradiation step in whichthe photomask is removed and parallel light continues to be irradiated.

In the first irradiation step, the photopolymerizable compositionirradiated by parallel light is not completely polymerized byphotopolymerization, and is preferably polymerized to a polymerizationdegree of 10%-80%, which only determines the formation positions of thecolumnar structures.

This is because in the first irradiation step, due to the spreading oflight by diffraction of the parallel light passing through the opticallytransmissive regions of the photomask, light reaches a portion of thematrix where there is not actually any need for irradiation, such thatwhen parallel light is irradiated to the entire surface in the secondirradiation step which follows, there ceases to be a significantdifference in index of refraction between the matrix and the columnarstructures.

Therefore in the present invention, polymerization of the whole iscompleted in the second irradiation step by irradiating the entiretywith parallel light, starting from an incompletely polymerized state inwhich there is some degree of difference in the polymerization degreebetween the matrix and the columnar structures within thephotopolymerizable composition.

By thus irradiating the photopolymerizable composition with parallellight, a significant index of refraction difference is imparted betweenthe two due to the cross link density difference relative to the matrixcaused by the columnar structure polymer self-accelerating effect, andthe composition distribution caused by reaction diffusion between thecolumnar structures and the matrix; also, columnar structures with ahigh aspect ratio extending in the direction of the parallel light, aswell as an obvious phase structure, can be formed.

In a preferred embodiment of the present invention, a large number ofthe optically transmissive regions of the photomask are disposed in aregular lattice. This enables the manufacture of a molded product inwhich regular columnar structures are formed, half widths are narrow,and a sharp diffraction spot are imparted.

Effect of the Invention

The present invention is a molded product having a phase structureformed by photopolymerization of a photopolymerizable composition, andprovides a molded product and manufacturing method thereof for a moldedproduct imparting a sharp diffraction spot at a high diffractionefficiency. Due to those optical characteristics, the molded productabove can be used as an optical low-pass filter or the like.

BEST MODE FOR PRACTICING THE INVENTION

Below we discuss an embodiment wherein a molded product of the presentinvention is used as a film-shaped light diffraction element.

As shown in FIG. 1, molded product 1 contains a phase separationstructure comprising a matrix 2, consisting of a thin plate substrate ofa photopolymerized composition, and columnar structures 3, consisting ofphotopolymerized compositions disposed within the matrix 2. The columnarstructures 3 have an index of refraction different from that of thematrix 2. The molded product 1 is formed in a film shape with anapproximately fixed thickness.

Generally used film shapes are appropriate for the molded product of thepresent invention as a material for optical use. However, in the moldedproduct of the present invention, the shape thereof can be determinedappropriately according to need, therefore it is not limited to filmshapes, but may also be formed into other shapes. For example, themolded product may have a shape whereby its thickness varies in thelongitudinal direction.

Each of the columnar structures 3 has approximately the same shape, andis disposed in a regular triangle lattice so that the axes thereofextend in the thickness direction of the film-shaped molded product 1.More specifically, the columnar structures 3 have a cylindrical shapewith an approximately fixed cross sectional shape in the axialdirection; the multiple columnar structures 3 are oriented approximatelyin parallel such that their axial direction A is the same direction, andthe shape of the cross sections thereof perpendicular to the axialdirection A are made to be approximately the same.

In the columnar structures 3, the axial direction A and the moldedproduct thickness direction B are set to be approximately the same, butnot limited thereto; a specified angle may also be established betweenthese directions A and B. Also, the columnar structures are set to becircular in cross section, but they are not limited thereto, and mayalso be elliptical, rectangular, or the like.

Multiple columnar structures 3 are arranged in a regular trianglelattice within the plane perpendicular to the axial direction A, but themultiple columnar structures 3 may also be disposed in a specifiedpattern. The specified pattern may be, for example, any desired latticeshape such as a square lattice shape or the like.

Thus the molded product 1 includes a phase structure comprising a matrix2 and columnar structures 3 disposed within the matrix 2.

Therefore when light from the plane direction is incident on the moldedproduct 1, the molded product 1 imparts a diffraction spot due to thelayout of the columnar structures 3, and functions as a diffractionelement.

Next we discuss the method for manufacturing the molded product 1.

To manufacture the molded product 1, a photopolymerizable composition 20is injected into a mold 10, and then a photomask 40 is disposed betweenan irradiation light source 30 and the mold 10 (see FIGS. 2 through 6).Thereafter, light from the irradiation light source 30 is directed atand irradiated onto the photopolymerizable composition 20 in the mold10; the photomask 40 is removed and light from the irradiation lightsource 30 is further directed at and irradiated onto thephotopolymerizable composition 20 in the mold 10. Photopolymerization ofthe photopolymerizable composition 20 is thus completed. By removing thenow completely polymerized photopolymerizable composition 20 from themold 10, the molded product 1 transparent to the intended usagewavelengths can be obtained.

(Mold)

Referring to FIG. 2, we now discuss the mold 10 used in the method formanufacturing the molded product 1. FIGS. 2( a) and (b) are respectivelya plan view and a cross section of the mold 10 into which thephotopolymerizable composition 20 is filled.

The mold 10 comprises a main unit 11 having a space portion (concavity)11 a, and a cover piece 12 covering the space portion 11 a. By coveringthe main unit 11 with the cover piece 12, a cavity defined by the spaceportion 11 a is formed inside the mold 10. As will be discussed below,the photopolymerizable composition 20 is injected into this cavity andheld there. It is desirable that the photopolymerizable composition 20filled into the cavity not contact external air, so as to avoidinhibition of polymerization by oxygen. For this reason, the mold 10 canfluid-seal the photopolymerizable composition 20.

To form the film-shaped molded product 1, the space portion 11 a of themain unit 11 creates a thin film or thin plate-shaped space. However,the space portion 11 a can be given a variety of shapes according to theshape of the molded product 1 being formed.

Since the cover piece 12 is disposed on the light irradiation side whenmanufacturing the molded product 1, a light-transmissive material withlow optical absorption of the irradiation light source wavelength isused; average thickness is 150 μm. Specifically, the light-transmissivematerial is Pyrex (registered trademark) glass, quartz glass,fluorinated (meth)acrylic resin, or the like.

Below we discuss materials usable for the photopolymerizable composition20.

(Multifunctional Monomers)

It is desirable that a multifunctional monomer be included in thephotopolymerizable composition 20. As multifunctional monomers of thistype, (meth)acryl monomers containing a (meth)acryloyl group, vinylgroups, and allyl groups and the like are particularly preferable.

Specific examples of multifunctional monomers include triethyleneglycoldi(meth)acrylate, polyethylene glycol di(meth)acrylate, neopentylglycoldi(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanedioldi(meth)acrylate, hydrogenated dicyclopentadienyl di(meth)acrylate,ethylene oxide denatured bisphenol A di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate,tetramethylolmethane tetra(meth)acrylate, pentaerythritolhexa(meth)acrylate, multifunctional epoxy (meth)acrylate,multifunctional urethane (meth)acrylate, divinylbenzene, triallylcyanurate, triallyl isocyanurate, triallyl trimellitate, diallylchlorendate, N,N′-m-phenylenebismaleimide, and diallyl phthalate; thesemay be used alone in or in blends of two or more.

Among these, multifunctional monomers with three or more polymerizingcarbon-carbon double bonds in the molecule lead to large refractiveindex difference caused by polymerization, making it easier for theabove-described columnar structures to form.

Particularly preferred multifunctional monomers having three or morepolymerizing carbon-carbon double bonds are trymethylol propanetri(meth)acrylate, pentaerythritol tetra(meth)acrylate, tetramethylolmethane tetra(meth)acrylate, and pentaerythritol hexa(meth)acrylate.

When two or more types of multifunctional monomers or oligomers thereofare used as the photopolymerizable composition 20, it is preferable touse polymers whose indexes of refraction as homopolymers differ betweenone another, and it is more preferable to combine those having greaterdifferences in index of refraction.

In order to assure that functions such as diffraction, polarization, anddiffusion are obtained at a high efficiency requires larger refractionindex differences; it is preferable that the difference in index ofrefraction be 0.01 or greater; 0.05 or greater is more preferred.Diffusion of the monomer in the polymerization process causesdifferences in index of refraction to increase, therefore combinationswith a large differential in diffusion constants are preferred.

Note that when using three or more types of multifunctional monomer oroligomer, arrangements should be made so that the index of refractiondifference between at least two of the homopolymers falls within therange noted above. In order to obtain functions such as high efficiencydiffraction, polarization, and diffusion, it is preferable that the twomonomers or oligomers with the greatest difference in index ofrefraction as homopolymers be used in ratios of between 10:90 and 90:10by weight.

(Multifunctional Monomers)

Together with the above noted multifunctional monomers and oligomers,monofunctional monomers or oligomers having a single carbon-carbondouble bond in the molecule can also be used in the photopolymerizablecomposition 20. Particularly preferred such monofunctional monomers andoligomers are (meth)acrylic monomers containing a (meth)acryloyl group,and containing a vinyl group, and allyl group, or the like.

Specific examples of monofunctional monomers include acrylate compoundssuch as methyl (meth)acrylate, tetrahydro furfuryl (meth)acrylate, ethylcarbitol (meth)acrylate, dicyclo pentanyl oxyethyl (meth)acrylate,isobornyl (meth)acrylate, phenyl carbitol (meth)acrylate, nonylphenoxyethyl (meth)acrylate, 2-hydroxy-3-phenoxy propyl (meth)acrylate,(meth)acryloyloxy ethyl succinate, (meth)acryloyloxy ethyl phthalate,phenyl (meth)acrylate, cyanoethyl (meth)acrylate, tribromophenyl(meth)acrylate, phenoxyethyl (meth)acrylate, tribromo phenoxyethyl(meth)acrylate, benzyl (meth)acrylate, p-bromobenzyl (meth)acrylate,2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, trifluoroethyl(meth)acrylate, and 2,2,3,3-tetrafluoropropyl (meth)acrylate; vinylcompounds such as styrene, p-chlorostyrene, vinyl acetate, acrylonitryl,N-vinyl pyrrolidone, and vinylnaphthalene; and allyl compounds such asethylene glycol bis-allyl carbonate, diallyl phthalate, and diallylisophthalate.

These monofunctional monomers or oligomers are used to impartflexibility to the molded product 1; a preferred range for their userelative to multifunctional monomers or oligomers is 10-99% by mass; amore preferred range is 10-50% by mass.

(Polymers, Low Molecular Weight Compounds)

It is also possible in the photopolymerizable composition 20 to useuniformly dissolving mixtures containing compounds which do not havepolymerizing carbon-carbon double bonds with the multifunctionalmonomers or oligomers.

Examples of compounds which do not have polymerizing carbon-carbondouble bonds include polymers such as polystyrene, polymethyl(meth)acrylate, polyethylene oxide, polyvinylpyrrolidone, polyvinylalcohol, and nylon; low molecular weight compounds such as toluene,n-hexane, cyclohexane, acetone, methyl ethyl ketone, methyl alcohol,ethyl alcohol, ethyl acetate, acetonitryl, dimethyl acetone amide,dimethylformamide, tetrahydrofuran; and additives such as organichalogen compounds, organic silicon compounds, plasticizers, andstabilizers.

Compounds like this which do not have polymerizing carbon-carbon doublebonds are used for such purposes as adjusting the viscosity of thephotopolymerizable composition 20 when manufacturing the molded product1 in order to make easier to handle, or reducing the monomer componentratio in the photopolymerizable composition 20 to improve polymerizationdegree; the amount used thereof is preferably in a range of 1-99% bymass of the total amount of multifunctional monomer or oligomer, andmore preferably in a range of 1-50% by mass thereof, in order to improvehandling qualities while forming columnar structures with a regulararrangement.

(Photoinitiator)

There is no particular limitation as to photoinitiators used in thephotopolymerizable composition 20, so long as the initiator is onenormally used for photopolymerization in which polymerizing is done byirradiating with an active energy beam such as ultraviolet or the like.Examples include benzophenone, benzyl, Michler's ketone,2-chlorothioxanthone, benzoine ethyl ether, dietoxyacetophenone,p-t-butyl trichloroacetophenone, benzyl dimethyl ketal,2-hydroxy-2-methyl propyl phenone, 1-hydroxycyclohexyl phenyl ketone,and 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanon-1, dibenzosuberon.

A preferred range for use of these photoinitiators relative to theweight of other photopolymerizable compositions is 0.001-10% by mass; amore preferred range in order to avoid loss of transparency of themolded product 1 is 0.01-5% by mass.

Referring to FIGS. 3 through 6, we now discuss other equipment used inthe method for manufacturing the molded product 1.

(Photomask)

In the molded product 1, multiple columnar structures 3 with indexes ofrefraction different from that of the matrix 2 are oriented in the samedirection within the matrix 2; the columnar structures 3 are disposed ina certain pattern within a plane perpendicular to this orientationdirection. This pattern can be determined as desired using texturingfrom the photomask 40.

In the present embodiment, texturing is used as a method for determiningthe position of the columnar structures 3. The texturing referred tohere is a method for imparting a high level of regularity to thecolumnar structures 3 to be formed by pre-inputting positioninformation.

A photomask used for photolithography or the like can be used as thephotomask 40. There is no particular rule regarding the size, pitch, orshape of mask hole patterns or hole diameters, but if the mask holes arecircular, the hole diameter is preferably 80 nm-10 μm, and pitch ispreferably 120 nm-15 μm.

As shown in FIG. 3, the photomask 40 is one in which mask holes 41 areregularly arranged in a triangular lattice pattern. The mask holes 41may be arranged in other patterns, not limited to the above. Forexample, as shown in FIG. 4, a photomask 40 may be used in which themask holes 41 are regularly arranged in a square lattice pattern.

Note that in the present embodiment, although texturing by the photomask40 is used to form the columnar structures 3, there is no limitationthereto, and position information may also be input using scanningirradiation with laser light from a visible or ultraviolet regionwavelength band, or X rays, or γ rays or the like.

(Irradiation Light Source)

A [source] capable of irradiating the mold 10 with parallel light suchas ultraviolet or the like is used for the irradiation light source 30(see FIG. 6). The degree of parallelness of irradiated light ispreferably such that the spreading angle is ±0.03 rad or less, and morepreferably ±0.001 rad or less.

In addition to the ability to irradiate with parallel light, the lightsource used for the irradiation light source 30 is capable of keepingthe parallel light intensity distribution essentially uniform within thevertical cross section relative to the direction of advance of theirradiated parallel light. Specifically, a light source in whichparallel light from a point light source or a stick light source has anessentially uniform light intensity distribution (hat shapeddistribution) using a mirror or lens or the like, or a planar lightsource such as a VCSEL, can be used as the irradiation light source 30.

Note that laser light is preferable from the standpoint of parallelness,but due to its Gaussian distribution of light intensities, it ispreferably used with an appropriate filter or the like to make thedistribution of light intensity essentially uniform.

In other words, for the molded product 1 it is necessary to advance thepolymerization reaction uniformly in a plane perpendicular to the filmthickness direction B of the molded product 1 in order to arrange thecolumnar structures 3 with a high degree of regularity. For this reason,the light intensity distribution of the irradiation light source 30 isset to be essentially uniform within the irradiation range.

In the irradiation light source 30, as shown in FIG. 5, an irradiationarea 31 is divided into multiple regions (9 regions in the presentembodiment); the light intensity is measured at points 31 a-31 i in eachregion, and 2.0% or below is used as the value for illumination leveldistribution given by Expression (2). More preferably, a value of 1.0%or below is used.

Illumination level=(max. value−min. value)/(max value+min. value)×100  (2)

(Light Irradiation)

In the method for manufacturing the molded product 1, light irradiationis implemented using two light irradiation steps, comprising a firstlight irradiation step and a second light irradiation step.

First Light Irradiation Step

In the first light irradiation step, as shown in FIG. 6( a), a photomask40 for determining the forming positions of the columnar structures 3 isfirst disposed on the top portion of the mold 10 filled with thephotopolymerizable composition 20 (i.e., between the mold 10 and theirradiation light source 30). At this point, the photomask 40 isdisposed essentially parallel to the top surface of the mold 10 (coverpiece 12). To more precisely control the circle diameter and pitch ofthe columnar structures, it is preferable that the distance from theuppermost surface of the photopolymerizable composition 20 to thephotomask 40 is 2 mm or less, and more preferably, 200 μm or less. Inthe method for determining a forming position using a photomask,attention must be paid to the point at which ultraviolet light isdiffracted at the mask aperture. Diffraction can cause the formingposition to be set in a pattern different from the photomask, or causethe pattern to degrade too greatly so that the forming position cannotbe determined; the distance between the photomask and thephotopolymerizable composition must therefore be accurately determined.

Next, after positioning the photomask 40, parallel light such asultraviolet light or the like, having a wavelength full width at halfmaximum of 100 nm or less in the irradiation range and an essentiallyuniform light intensity distribution, is irradiated from the irradiationlight source 30. This results in the irradiation of a specified patternin the photopolymerizable composition 20 caused by parallel lightpassing through the photomask 40. Thus, in the first light irradiationstep, ultraviolet light or the like is irradiated as parallel lightuntil the photopolymerizable composition 20 polymerizes to a gel state,thereby determining the forming positions of the columnar structures 3within the molded product 1.

Specifically, in the first light irradiation step, thephotopolymerizable composition 20 is irradiated until its polymerizationdegree is in the range of 10%-80%, and more preferably until it is in arange of 20%-60%, in order to accomplish the twin goals of regularityand high diffraction efficiency in the columnar structures 3 of themanufactured molded product 1.

In the present embodiment, in the Photo-DSC method, the state in whichthe photopolymerizable composition 20 has completely reacted so that nofurther heat is emitted even if irradiated with light is considered a100% of polymerization degree. In the first light irradiation step, aspecified amount of is irradiated on the photopolymerizable composition20 until the polymerization degree calculated from the calorific valuein the Photo-DSC method reaches a specified polymerization degree(10%-80%).

(Second Light Irradiation Step)

Following the first light irradiation step, in the second lightirradiation step shown in FIG. 6( b) the photomask 40 is removed, andthe mold 10 is further irradiated with parallel light having awavelength full width at half maximum of 100 nm or less and anessentially fixed light intensity distribution. Parallel light is thusirradiated onto the entirety of the photopolymerizable composition 20;each of forming sites of the columnar structure 3 and the matrix 2 whichwere predetermined in the first light irradiation step are formed in thefilm thickness direction, and the photopolymerizable composition 20 ispolymerized completely, while the difference in index of refractionbetween the matrix 2 and the columnar structures 3 is increased.

At this point, columnar structures 3 are clearly formed by parallellight within the matrix 2, in a way which does not broaden in the planardirection and extends parallel to the film thickness direction. Themolded product 1 is thus formed in a way that the change in index ofrefraction is clearly apparent at the boundary between the matrix 2 andthe columnar structures 3. The molded product 1 is manufactured byparting the completely polymerized photopolymerizable composition 20from the mold 10.

In general, the resolution when exposing light emitted from a pointsource such as a high pressure mercury lamp or the like and adjusted forillumination level uniformity and parallelness by mirrors or lenses on aphotomask is as follows. For a photomask slit width a and a gap L, lightpassing through the slit is approximated by Fresnel diffraction for thecase when the size of a is non-negligible relative to L (when the valuesa and L are close); when the size of a is negligible relative to L, onthe other hand (a<<L), it is approximated by Fraenhofer diffraction.When the degradation of the image caused by diffraction is representedby the function F in Expression (3), the resolution limit appears nearan F of 2. λ is the wavelength of light.

F=a(2/λL)^(1/2)   (3)

From Expression (3), we obtain a=0.89 L^(1/2) for the case when F=2 andλ=0.4. The term a is the resolving limit line width. If L is assumed tobe the 150 μm average thickness of the cell upper portion cover piece12, resolution is 10.9 μm. Therefore the hole diameter of the columnarstructures is 80 nm-10 μm, so even if one only attempts to form thecolumnar structures using a photomask, image degradation caused byFraenhofer diffraction (a<<L) is severe, and it is inconceivable thatcolumnar structures with an aspect ratio of 10 or greater would form ina system of this type.

In other words, when columnar structures are completely formed usingonly a first light irradiation step, as was conventionally the case,light passing through the photomask spreads due to diffraction from themask hole projection region (i.e. the columnar structure region) to thematrix region. This is why even when a second light irradiation step iscarried out, as is conventionally done after the first light irradiationstep, a significant difference in index of refraction does not arisebetween the matrix and the columnar structures.

However, in the present embodiment the first light irradiation step doesnot cause completely polymerizing of the columnar structures 3; it onlyaffixes the forming position. In the second light irradiation step, theentire [piece] is made to polymerize completely by irradiating parallellight onto the entire [piece], which is in an incompletely polymerizedstate, with some difference between the polymerization degree of thematrix 2 and the columnar structures 3. At this point a significantdifference in index of refraction is imparted between the two by thedifference in cross linking density between the columnar structures 3and the matrix 2 due to the polymer auto-acceleration effect, and bycomposition distribution due to reaction diffusion between the columnarstructures 3 and the matrix 2. It is also possible to form columnarstructures 3 with a high aspect ratio extending approximately parallelto the thickness direction of the molded product 1.

Evaluation of the molded product 1 was implemented as follows.

(Calculation of Diffraction Efficiency)

A laser beam with a standard normal intensity distribution wasirradiated onto a manufactured molded product 1 and the intensity of thediffraction spot measured; a value obtained by dividing the measuredintensity of the diffraction spot by the intensity of the entireincident light was calculated as the diffraction efficiency of themolded product 1. When multiple diffraction spots appear, the value ofthe total intensity of those spots divided by the entire incident lightis used.

In the present embodiment, the molded product 1 diffraction efficiencywas 10% or greater (10%≦diffraction efficiency≦100%).

(Angular Spectrum)

As shown in FIG. 7, a laser beam 52 with a standard normal intensitydistribution from a laser light source 51 was made perpendicularlyincident to the surface of the molded product 1, and the transmittedlight intensity from the molded product 1 was measured by a photodiode54 while varying the angle θ of the photodiode 54 with respect to themolded product 1 by angle varying means 53. Assuming that the point atwhich the directly advancing point of the transmitted incident laserbeam 52 is at 0°, that the horizontal axis has is at an angle θ, andthat the vertical axis is described using light intensity, an angularspectrum such as that shown in FIG. 8 is obtained. The half width of thediffraction spot was obtained from this angular spectrum. The higher theregularity of the columnar structure is arranged, the smaller the halfwidth of the peak.

In the present embodiment, the half width of the diffraction spotobtained from the angular spectrum for the molded product 1 was 0.6°(0°<half width ≦0.6°).

(Optical Low Pass Filter)

The molded product 1 may also be used for an optical low pass filter. Inimage capture systems such as digital cameras and the like, moiré (falsecolor) frequently presents problems. This occurs because CCD or CMOSsensors are regularly arranged, and therefore create interference withregular patterns included in the imaged object. One means of resolvingthis problem is to introduce an optical low pass filter. An optical lowpass filter reduces the effect of interference by separating incidentlight at multiple points, thereby suppressing moiré.

To use the molded product 1 as an optical low pass filter, an opticallaminate is formed by laminating transparent optical elements (e.g.transparent film or the like) onto the molded product 1, or by formingthe molded product 1 as one piece with a supporting glass substrate.This optical laminate diffracts incident light at a specific positionand intensity, and can therefore function as an optical low pass filterby appropriately setting the diffraction angle and diffractionefficiency of the optical laminate, as well as the distance relative tothe sensor described above.

In a Wafer Level Chip Size Package (WL-CSP), which is one method offabricating a sensor, a protective glass for protecting a sensor on asilicon substrate is laminated on using an adhesive layer. Using anoptical laminate as the WL-CSP protective glass facilitates setting thedistance with respect to the sensor, and enables the introduction of anoptical low pass filter to the sensor without losing the advantages ofWL-CSP's small size and high throughput advantages. This method makes iteasy to set the distance between the optical laminate and the sensorusing the thickness of the adhesive layer, and to implement an opticallow pass filter without increasing the thickness of the optics as awhole.

After forming an optical laminate with a large surface area in which themolded product 1 and the glass are formed as a single piece, thislaminate may be cut into specified sizes, and optical laminates cut tothe specified size may be used as protective glass on the sensor pieces.

Note that if the molded product 1 can be arranged in the optical system,an optically transparent optical element does not necessarily have to belaminated onto the molded product 1.

As an example, imaging optics 50 using a molded product 1 are shown inFIG. 9. These imaging optics 50 comprise a sensor 51, which is a fixedimaging element, an optical laminate 52, and a lens 53. In this example,the optical laminate 52 is constituted by forming the molded product 1and a glass substrate 4 as a single piece; this is used as an opticallow pass filter. This optical laminate 52 is affixed to the lightreceiving surface of the sensor 51 by an adhesive layer 6 disposed onthe outside edge portion thereof. A gap layer of a specified thicknessis thus formed between the optical laminate 52 and the sensor 51. Thisgap layer is an air layer.

Note that in the FIG. 9 example, the adhesive layer 6 is disposed onlyon the outside edge portion of the optical laminate 52, but it is notlimited thereto, and an adhesive layer may be disposed over the entireoptical laminate 52, affixing the optical laminate 52 and the sensor 51.In that case, the gap layer is the adhesive layer.

(Silane Coupling)

A method for forming the molded product 1 as a single piece with theglass substrate is to adhere the two using a silane coupling agent.There is no particular limitation on what can be used as the silanecoupling agent so long is it is a compound having both a reaction sitefor bonding with an inorganic component such as glass (e.g. a siteproducing an ethanol group by hydrolysis), and a site reacting with anorganic component (e.g. functional groups such as a (meth)acryloylgroup, epoxy group, vinyl group, or amino group). A glass substratewhich has been surface treated in advance with a silane coupling agentmay also be used, and a silane coupling agent may also be incorporatedinto the photopolymerizable composition.

(Infrared Blocking Function)

The glass substrate is not particularly limited to inorganic glass orthe like generally in use, but because a luminosity factor correction isrequired when using CCDs or the like as a sensor, it is preferable tohave a function for blocking light in the near infrared region.

An infrared blocking functionality can also be imparted to the moldedproduct by adding an infrared absorption agent to the photopolymerizablecomposition.

To use the molded product 1 as an optical low pass filter, it ispreferable that the surface has an anti-reflective capability. Examplesof anti-reflective treatment are electron beam lithography, as well as amethod for forming fine bump structures by stamping, using anodizedporous aluminum or the like.

An anti-reflective film may also be formed on surfaces by using acoating to impart anti-reflective capability.

Below we discuss the present invention more specifically usingembodiments.

First Embodiment

In a first embodiment, a photopolymerizable composition was obtained bydissolving 0.6 mass parts of 1-hydroxycyclohexyl phenyl ketone in amixture of 30 mass parts phenoxyethyl acrylate and 70 mass partstrimethylolpropane trimethacrylate.

The photopolymerizable composition obtained was inserted as a 20 mm φ,0.2 mm thick film into a glass cell. The glass was given a thickness of150 μm on the irradiation side. Next, a photomask on which 2 μm φlight-transmissive regions were arranged at a 5 μm pitch in a hexagonallattice (triangular lattice) was disposed on the top portion of theglass cell, and ultraviolet parallel light with an essentially uniformlight intensity distribution was irradiated thereon from a directionperpendicular to the surface, at 840 mJ/cm². The polymerization degreeof the photopolymerizable composition at this point was 40%.

Thereafter the photomask was removed, ultraviolet parallel light wasfurther irradiated at 6300 mJ/cm², the photopolymerizable compositionwas polymerized, and a plastic film was obtained.

FIG. 10 shows an optical micrograph of the plastic film obtained. It wasconfirmed from this observed image that the columnar structures wereregularly arranged in the manufactured plastic film.

An evaluation was made of the diffraction pattern by irradiating theplastic film from a perpendicular direction with a laser beam having ahalf width intensity distribution of 0.5°. FIG. 11 shows the observedimage of diffraction points caused by the regular phase structure insidethe polymer. From the angular spectrum of the diffraction image, theangular width (half width) at the first order diffraction points wasgood, at 0.5°. Diffraction efficiency was also good, at 75%.

Second Embodiment

In a second embodiment, the polymerization degree in the firstembodiment and the first light irradiation step were varied, andpolymerization degree was set at the upper limit value (80%).

In the second embodiment, the same photopolymerizable composition as inthe first embodiment was inserted as a 20 mm φ, 0.2 mm thick film into aglass cell. The glass was given a thickness of 150 μm on the irradiationside. Next, a photomask on which 2 μm φ light-transmissive regions werearranged at a 5 μm pitch in a hexagonal lattice was disposed on the topportion of the glass cell, and ultraviolet parallel light with anessentially uniform light intensity distribution was irradiated thereonfrom a direction perpendicular to the surface, at 1400 mJ/cm². Thepolymerization degree of the photopolymerizable composition at thispoint was 80%.

Thereafter the photomask was removed, ultraviolet parallel light wasfurther irradiated at 6300 mJ/cm², the photopolymerizable compositionwas polymerized, and a plastic film was obtained.

As in the first embodiment, an evaluation was made of the diffractionpattern by irradiating the obtained plastic film from a perpendiculardirection with a laser beam having a half width intensity distributionof 0.5°, and diffraction points caused by the regular phase structureinside the polymer were observed. From the angular spectrum of thediffraction image, the angular width (half width) at the first orderdiffraction points was 0.5°. Diffraction efficiency was 60%.

It was thus found that compared to the first embodiment, the half widthof the diffraction spot in the second embodiment was good, beingapproximately the same, and the diffraction efficiency was slightlyinferior, but still good at 10% or greater.

Note that the polymerization degree in first light irradiation step wasset at the upper limit value of 80% in the second embodiment, but evenwhen set at the lower limit value of 10%, a diffraction spot having ahalf width of 0.5—approximately the same as the first embodiment—wasobserved, and a good value for diffraction efficiency of 10% or abovewas confirmed.

Third Embodiment

In a third embodiment, the polymerization degree in the first embodimentand the first light irradiation step were varied, and polymerizationdegree was set at a near upper limit value (75%), while the pattern oflight-transmissive regions on the photomask was also varied (6 μm φ, 12μm pitch).

In the third embodiment, the same photopolymerizable composition as inthe first embodiment was inserted as a 20 mm φ, 0.2 mm thick film into aglass cell. The glass was given a thickness of 150 μm on the irradiationside. Next, a photomask on which 6 μm φlight-transmissive regions werearranged at a 12 μm pitch in a hexagonal lattice was disposed on the topportion of the glass cell, and ultraviolet parallel light with anessentially uniform light intensity distribution was irradiated thereonfrom a direction perpendicular to the surface, at 1260 mJ/cm². Thepolymerization degree of the photopolymerizable composition at thispoint was 75%.

Thereafter the photomask was removed, ultraviolet parallel light wasfurther irradiated at 6300 mJ/cm², the photopolymerizable compositionwas polymerized, and a plastic film was obtained.

As in the first embodiment, an evaluation was made of the diffractionpattern by irradiating the obtained plastic film from a perpendiculardirection with a laser beam having a half width intensity distributionof 0.5°, and diffraction points caused by the regular phase structureinside the polymer were observed. From the angular spectrum of thediffraction image, the angular width (half width) at the first orderdiffraction points was 0.5°. Diffraction efficiency was 30%.

It was thus found that compared to the first embodiment, the half widthof the diffraction spot in the third embodiment was good, beingapproximately the same, and the diffraction efficiency was slightlyinferior, but still good at 10% or greater.

Fourth Embodiment

In a fourth embodiment, polymerization degree was approximately the sameas in the first embodiment and the first light irradiation step (40%),but the pattern of the photomask light-transmissive regions was changedto one of a square lattice.

In the fourth embodiment, the same photopolymerizable composition as inthe first embodiment was inserted as a 20 mm φ, 0.2 mm thick film into aglass cell. The glass was given a thickness of 150 μm on the irradiationside. Next, a photomask on which 2 μm φ light-transmissive regions werearranged at a 5 μm pitch in a square lattice was disposed on the topportion of the glass cell, and ultraviolet parallel light with anessentially uniform light intensity distribution was irradiated thereonfrom a direction perpendicular to the surface, at 840 mJ/cm². Thepolymerization degree of the photopolymerizable composition at thispoint was 30%.

Thereafter the photomask was removed, ultraviolet parallel light wasfurther irradiated at 6300 mJ/cm², the photopolymerizable compositionwas polymerized, and a plastic film was obtained.

As in the first embodiment, an evaluation was made of the diffractionpattern by irradiating the obtained plastic film from a perpendiculardirection with a laser beam having a half width intensity distributionof 0.5°, and diffraction points caused by the regular phase structureinside the polymer were observed. From the angular spectrum of thediffraction image, the angular width (half width) at the first orderdiffraction points was 0.5°. Diffraction efficiency was 58%.

It was thus found that compared to the first embodiment, the half widthof the diffraction spot in the fourth embodiment was good, beingapproximately the same, and diffraction efficiency was slightlyinferior, but still good at 10% or greater.

Fifth Embodiment

A fifth embodiment was an example implemented in the same conditions asthe first embodiment, except that the photomask was arranged at 50 μmabove the glass on the irradiation surface side.

In the fifth embodiment, the same photopolymerizable composition as inthe first embodiment was encapsulated as a 20 mm φ, 0.2 mm thick filminto a glass cell. The glass was given a thickness of 150 μm on theirradiation side. Next, a photomask on which 2 μm φ light-transmissiveregions were arranged at a 5 μm pitch in a hexagonal lattice wasdisposed at 50 μm above the glass on the irradiation surface side, andultraviolet parallel light with an essentially uniform light intensitydistribution was irradiated thereon from a direction perpendicular tothe surface, at 840 mJ/cm². The polymerization degree of thephotopolymerizable composition at this point was 40%.

Thereafter the photomask was removed, ultraviolet parallel light wasfurther irradiated at 6300 mJ/cm², the photopolymerizable compositionwas polymerized, and a plastic film was obtained.

As in the first embodiment, an evaluation was made of the diffractionpattern by irradiating the obtained plastic film from a perpendiculardirection with a laser beam having a half width intensity distributionof 0.5°, and diffraction points caused by the regular phase structureinside the polymer were observed. From the angular spectrum of thediffraction image, the angular width (half width) at the first orderdiffraction points was 0.5°. Diffraction efficiency was 77%.

It was thus found that both the half width of the diffraction spot andthe diffraction efficiency in the fifth embodiment were good as the onesin the first embodiment.

Sixth Embodiment

A sixth embodiment was an example implemented in the same conditions asthe first embodiment, except that the photomask was arranged at 100 μmabove the glass on the irradiation surface side.

In the sixth embodiment, the same photopolymerizable composition as inthe first embodiment was encapsulated as a 20 mm φ, 0.2 mm thick filminto a glass cell. The glass was given a thickness of 150 μm on theirradiation side. Next, a photomask on which 2 μm φ light-transmissiveregions were arranged at a 5 μm pitch in a hexagonal lattice wasdisposed at 100 μm above the glass on the irradiation surface side, andultraviolet parallel light with an essentially uniform light intensitydistribution was irradiated thereon from a direction perpendicular tothe surface, at 840 mJ/cm². The polymerization degree of thephotopolymerizable composition at this point was 40%.

Thereafter the photomask was removed, ultraviolet parallel light wasfurther irradiated at 6300 mJ/cm², the photopolymerizable compositionwas polymerized, and a plastic film was obtained.

As in the first embodiment, an evaluation was made of the diffractionpattern by irradiating the obtained plastic film from a perpendiculardirection with a laser beam having a half width intensity distributionof 0.5°, and diffraction points caused by the regular phase structureinside the polymer were observed. From the angular spectrum of thediffraction image, the angular width (half width) at the first orderdiffraction points was 0.5°. Diffraction efficiency was 20%.

It was thus found that compared to the first embodiment, the half widthof the diffraction spot in the sixth embodiment was good, beingapproximately the same, and diffraction efficiency was slightlyinferior, but still good at 10% or greater.

Seventh Embodiment

A seventh embodiment was an example implemented in the same conditionsas the first embodiment, except that the photomask was arranged at 1 mmabove the glass on the irradiation surface side.

In the seventh embodiment, the same photopolymerizable composition as inthe first embodiment was encapsulated as a 20 mm φ, 0.2 mm thick filminto a glass cell. The glass was given a thickness of 150 μm on theirradiation side. Next, a photomask on which 2 μm φ light-transmissiveregions were arranged at a 5 μm pitch in a hexagonal lattice wasdisposed at 1 mm above the glass on the irradiation surface side, andultraviolet parallel light with an essentially uniform light intensitydistribution was irradiated thereon from a direction perpendicular tothe surface, at 840 mJ/cm². The polymerization degree of thephotopolymerizable composition at this point was 45%.

Thereafter the photomask was removed, ultraviolet parallel light wasfurther irradiated at 6300 mJ/cm², the photopolymerizable compositionwas polymerized, and a plastic film was obtained.

As in the first embodiment, an evaluation was made of the diffractionpattern by irradiating the obtained plastic film from a perpendiculardirection with a laser beam having a half width intensity distributionof 0.5°, and diffraction points caused by the regular phase structureinside the polymer were observed. From the angular spectrum of thediffraction image, the angular width (half width) at the first orderdiffraction points was 0.5°. Diffraction efficiency was 15%.

It was thus found that compared to the first embodiment, the half widthof the diffraction spot in the seventh embodiment was good, beingapproximately the same, and diffraction efficiency was slightlyinferior, but still good at 10% or greater.

Comparative Example 1

In Comparative Example 1, in contrast to the first embodiment, no firstlight irradiation step was conducted using a photomask (i.e., thepolymerization degree in the first light irradiation step was 0%), andonly the second light irradiation step was carried out.

In Comparative Example 1, the same photopolymerizable composition as inthe first embodiment was inserted as a 20 mm φ, 0.2 mm thick film into aglass cell. The glass was given a thickness of 150 μm on the irradiationside. Next, ultraviolet parallel light with an essentially uniform lightintensity distribution was irradiated thereon from a directionperpendicular to the surface, at 6300 mJ/cm², the photopolymerizablecomposition was polymerized, and a plastic film was obtained.

FIG. 12 shows an optical micrograph of the plastic film obtained. It wasconfirmed from this observed image that the regularity of the columnarstructures was lower than plastic film of the first embodiment.

An evaluation was made of the diffraction pattern by irradiating theplastic film from a perpendicular direction with a laser beam having ahalf width intensity distribution of 0.5°. FIG. 13 shows the observedimage of diffraction points caused by the regular phase structure insidethe polymer. From the angular spectrum of the diffraction image, theangular width (half width) at the first order diffraction points was1.3°. Diffraction efficiency was 24%.

It was thus understood that while a diffraction efficiency value ofgreater than 10% was obtained for Comparative Example 1 compared to thefirst embodiment, regularity of the phase structure was low, thereforethe half width in the angular spectrum of the diffraction spot wasgreater than 0.6°.

Comparative Example 2

Comparative Example 2is one in which, in contrast to the firstembodiment, polymerization is essentially completed in the first lightirradiation step.

In Comparative Example 2, the same photopolymerizable composition as inthe first embodiment was inserted as a 20 mm φ, 0.2 mm thick film into aglass cell. The glass was given a thickness of 150 μm on the irradiationside. Next, a photomask on which 2 μm φ light-transmissive regions werearranged at a 5 μm pitch in a hexagonal lattice was disposed on the topportion of the glass cell, and ultraviolet parallel light with anessentially uniform light intensity distribution was irradiated thereonfrom a direction perpendicular to the surface, at 15 J/cm². Thepolymerization degree of the photopolymerizable composition at thispoint was 90%.

Thereafter the photomask was removed, ultraviolet parallel light wasfurther irradiated at 6300 mJ/cm², the photopolymerizable compositionwas polymerized, and a plastic film was obtained.

When an evaluation was made of the diffraction pattern by irradiatingthe plastic film from a perpendicular direction with a laser beam havinga half width intensity distribution of 0.5°, as in the first embodiment,diffraction points caused by the regular phase structure inside thepolymer were observed. From the angular spectrum of the diffractionimage, the angular width at the first order diffraction point was 0.5°.Diffraction efficiency was 6%.

It was thus understood that while the diffraction spot half width inComparative Example 2 was good, being about the same as the firstembodiment, the value shown for diffraction efficiency was not good, atunder 10%.

Comparative Example 3

A comparative example 3 was an example implemented in the sameconditions as the first embodiment, except that the photomask wasarranged at 5 mm above the glass on the irradiation surface side.

In Comparative Example 3, the same photopolymerizable composition as inthe first embodiment was encapsulated as a 20 mm φ, 0.2 mm thick filminto a glass cell. The glass was given a thickness of 150 μm on theirradiation side. Next, a photomask on which 2 μm φ light-transmissiveregions were arranged at a 5 μm pitch in a hexagonal lattice wasdisposed at 5 mm above the glass on the irradiation surface side, andultraviolet parallel light with an essentially uniform light intensitydistribution was irradiated thereon from a direction perpendicular tothe surface, at 840 mJ/cm². The polymerization degree of thephotopolymerizable composition at this point was 30%.

Thereafter the photomask was removed, ultraviolet parallel light wasfurther irradiated at 6300 mJ/cm², the photopolymerizable compositionwas polymerized, and a plastic film was obtained.

When an evaluation was made of the diffraction pattern by irradiatingthe plastic film from a perpendicular direction with a laser beam havinga half width intensity distribution of 0.5°, as in the first embodiment,diffraction points caused by the regular phase structure inside thepolymer were observed. From the angular spectrum of the diffractionimage, the angular width at the first order diffraction point was 0.5°.Diffraction efficiency was 5%.

It was thus understood that while the diffraction spot half width inComparative Example 3 was good, being about the same as the firstembodiment, the value shown for diffraction efficiency was not good, atunder 10%.

Eighth Embodiment

Eighth embodiment is an example of a molded product formed as a singlepiece with a glass substrate. A silane coupling agent dilute solutionwas prepared by diluting KBM5103 (3-acryloxypropyltrimethoxysilane;Shin-Etsu Chemical Industries) in a 2.0% acetic acid aqueous solution.The surface of a 200 mm φ, 500 μm thick glass substrate was treated withthe above-described silane coupling agent to obtain a silane couplingagent-treated glass substrate. A 100 μm thickness of aphotopolymerizable composition of the same composition as the firstembodiment was coated onto this glass substrate, and a molded productwas obtained by covering and sealing the photopolymerizable composition,coated using a polyethylene terephthalate film as a transparent coverpiece. Next, a photomask on which 2 μm φ light-transmissive regions werearranged at a 5 μm pitch in a hexagonal lattice was disposed on the topportion of the glass cell, and ultraviolet parallel light with anessentially fixed light intensity distribution was irradiated thereonfrom a direction perpendicular to the surface, at 840 mJ/cm². Thepolymerization degree of the photopolymerizable composition at thispoint was 30%.

Thereafter the photomask was removed, ultraviolet parallel light wasfurther irradiated at 6300 mJ/cm², the photopolymerizable compositionwas polymerized, the transparent cover piece peeled off, and an opticallaminate in which the molded product was formed as a single piece withthe glass substrate was obtained.

When an evaluation was made of the diffraction pattern by irradiatingthe obtained optical laminate from a perpendicular direction with alaser beam having a half width intensity distribution of 0.5°, as in thefirst embodiment, diffraction points caused by the regular phasestructure inside the polymer were observed. From the angular spectrum ofthe diffraction image, the angular width (half width) at the first orderdiffraction point was 0.5°. Diffraction efficiency was 75%.

Positioning of the optical low pass filter was easily achieved when thisoptical laminate was used as an optical low pass filter and mounted on afixed image sensor through an adhesive layer. It was confirmed that whenan imaging optical system was fabricated using a fixed imaging elementthus mounted with an optical low pass filter and circular zone plate wasimaged, moiré in a region containing a high spatial frequency componentwas suppressed.

BRIEF EXPLANATION OF FIGURES

FIG. 1 An overview diagram of the molded product of the presentinvention.

FIG. 2 An explanatory diagram of a mold for manufacturing the moldedproduct of the present invention.

FIG. 3 A plan view of a photomask used in the manufacturing method ofthe present invention.

FIG. 4 A plan view of a photomask used in the manufacturing method ofthe present invention.

FIG. 5 An explanatory diagram showing the measurement point for theillumination distribution of the irradiation light source used in themanufacturing method of the present invention.

FIG. 6 A diagram explaining the manufacturing method of the presentinvention.

FIG. 7 A summary diagram explaining the method for measuring the laserdiffraction angular spectrum of the molded product of the presentinvention.

FIG. 8 A graph of the angular spectrum obtained from the molded productof the present invention.

FIG. 9 An explanatory diagram of imaging optics using the molded productof the present invention.

FIG. 10 A diagram showing an optical micrograph of the molded product ofthe first embodiment.

FIG. 11 A diagram showing a laser diffraction image using the moldedproduct of the first embodiment.

FIG. 12 A diagram showing an optical micrograph of the molded product ofComparative Example 1.

FIG. 13 A diagram showing a laser diffraction image using the moldedproduct of Comparative Example 1.

DESCRIPTION OF REFERENCE NUMERALS

-   1 Molded product-   2 Matrix-   3 Columnar structure-   10 Mold-   11 Main unit-   12 Cover piece-   20 Photopolymerizable composition-   30 Irradiation light source-   40 Photomask

1. A molded product having a phase structure comprising a matrix andmultiple columnar structures disposed within said matrix and having anindex of refraction different from said matrix, wherein the half widthof a diffraction spot is 0.6° or less and diffraction efficiency is 10%or greater in an angular spectrum obtained by irradiation with a laserbeam having an intensity distribution of standard normal distributionand a half width of the intensity distribution of 0.5°.
 2. An opticallaminate comprising the molded product of claim 1 and an opticallytransparent film laminated thereto.
 3. An optical laminate comprisingthe molded product of claim 1 and a glass substrate formed as a singlepiece with this molded product so as to support the molded product. 4.An optical low pass filter using the optical laminate of claim 2 or 3.5. An imaging optical system comprising a fixed image sensor and theoptical low pass filter of claim 4 disposed on the photo-detectionsurface of this image sensor via a gap layer.
 6. A method formanufacturing a molded product having a phase structure, comprising amatrix formed of a photopolymerizable composition, and multiple columnarstructures disposed within said matrix and having an index of refractiondifferent from said matrix, comprising: a step for injecting aphotopolymerizable composition containing a photopolymerizable monomeror oligomer and a photoinitiator into a mold; a step for disposing aphotomask having light-transmissive regions and a light non-transmissiveregion between the mold and a light source; a first light irradiationstep for irradiating parallel light from the light source with awavelength full width at half maximum of 100 nm or less and anessentially uniform light intensity distribution through the photomasktoward the photopolymerizable composition within the mold to polymerizethose sites within the photopolymerizable composition which areirradiated with parallel light into an incompletely polymerized state;and a second light irradiation step for irradiating parallel light witha wavelength full width at half maximum of 100 nm or less and anessentially uniform light intensity distribution toward thephotopolymerizable composition within the mold after removing thephotomask to complete the polymerization of the photopolymerizablecomposition.
 7. A method for manufacturing the molded product in claim6, whereby in the first light irradiation step, the photopolymerizablecomposition is polymerized to a polymerization degree of 10% or greaterand 80% or less.